[Adiponectin regulates the expression of osteoprotegerin and receptor activator of nuclear factor-kappaB ligand in human osteoblast].
OBJECTIVE
To investigate the possible mechanism by which adiponectin influences the osteoclastogenesis.


METHODS
Human osteoblasts were cultured in vitro and adiponectin of the concentrations 0, 3, 10, and 30 microg/ml were added for 48 hours to investigate the dose-dependent effect on the mRNA and protein expression of osteoprotegerin (OPG) in osteoblasts, and adiponectin of the concentrations 0 or 30 microg/ml was added for 0-48 hours to investigate the time-dependent effect. Fluorescent quantitation PCR and ELISA were used to detect the expression of OPG and receptor activator of nuclear factor-kappaB ligand (RANKL). Other human osteoblasts were cultured with CD14 + peripheral blood mononuclear cells (PBMCs), and incubated together with adiponectin of the concentration of 30 microg/ml for 14 days, and then stained by antitartaric acid phosphatase, a marker enzyme of osteoclast.


RESULTS
The expression levels of mRNA and protein of OPG in osteoblasts were 100% +/- 9%, 68% +/- 7%, 47% +/- 8%, and 30% +/- 5%, and (9.2 +/- 0.3), (6.6 +/- 0.4), (4.1 +/- 0.4), and (2.6 +/- 0.4) ng/ml respectively after incubation with adiponectin of the concentrations of 0, 3, 10, and 30 microg/ml for 48 hours. The mRNA and protein expression levels of RANKL were 100% +/- 5%, 165% +/- 8%, 213% +/- 6%, and 316% +/- 10%, and (1.3 +/- 0.2), (2.1 +/- 0.1), (2.3 +/- 0.2), and (2.8 +/- 0.1) ng/ml respectively. Adiponectin inhibited the osteoblast OPG expression and promoted the osteoblast RANKL expression dose- and time-dependently (P < 0.05). Adiponectin induced the osteoclast formation in the coculture systems of osteoblast and PBMCs systems.


CONCLUSIONS
Adiponectin increases osteoclast formation via stimulating RANKL and inhibiting OPG production in the osteoblasts, which may be one of the mechanisms adiponectin influences the osteoclastogenesis thereby.
Zhang
Xiang-Mei
XM
Department of Obstetrics & Gynecology, Second Xiangya Hospital of Central South University, Changsha 410011, China.
Xie
Hui
H
Yuan
Ling-Qing
LQ
Luo
Xiang-Hang
XH
Liao
Er-Yuan
EY
D052242:Adiponectin / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D052242:Adiponectin; D053244:Osteoprotegerin; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B